4130 vs 4140 Steel: Material Ultimate Guide

AISI 4130 and AISI 4140 steels belong to family of medium carbon low alloy steels. Major alloying elements involve carbon, chromium and molybdenum. Major difference in these steels is their carbon content. Due to higher percentage of carbon in AISI 4140, it is a strong candidate in high strength applications than AISI 4130. The application where good weldability and relativity high strengths are prime concern, AISI 4130 is the best choice for designers. In this article you will get a deep insight into the technical comparison of AISI 4130 and AISI 4140.

What is 4130 Steel

AISI 4130 has carbon content in the range of 0.28-0.33 wt.% carbon. It is used in automotive, aerospace, tools, bicycles and oil & gas industry. It is also famous as chromoly alloy.

What is 4140 Steel

AISI 4140 is a chrome-moly steel. 0.38-0.48 wt.% carbon is found in 4140 which imparts higher hardness than 4130. It is stronger than carbon steel. 4140 steel equivalent is 25CrMo₄.

Is 4140 alloy steel magnetic?

Yes, it is magnetic. Heat treatment and carbon content can influence the magnetic properties of 4041. Higher the carbon content, magnetic response will be more prominent.

Is 4140 high carbon steel?

No, it is not high carbon steel but considered as low alloy steel.

Difference Between 4130 and 4140

Chemical Properties of Steel 4130 and 4140

Except percentage carbon content, chemical composition of AISI 4130 and AISI 4140 is same. Chemical composition in weight percentage is given in below table:

Higher carbon content of AISI 4140 is responsible of its high hardness and superior strength. After carbon, chromium and molybdenum are prime contributor to increase hardenability and strength of 4130 and 4140 steel.

Physical Properties

AISI 4130 and AISI 4140 belong to same family of steels having a slight change in their carbon content. The physical properties of both steels are almost same.

1. Density: Density of AISI 4130 and AISI 4140 is same i.e., 7.85 g/cm³.
2. Ferromagnetic: Both steels are ferromagnetic at room temperature. It is an important property which is used to separate scrape of AISI 4130 and AISI 4140 from stainless steel scrape.
3. Melting Point: Melting point of both alloys is ~1432 ˚C.
4. Poisson ratio: Poisson’s ratio of both steels is around 0.27.

4130 vs 4140 Steel Properties

Mechanical properties of AISI 4130 and AISI 4140 are directly linked with their heat treatment condition and processing history. Normalizing, annealing and spheroidizing heat treatment process of AISI 4130 and AISI 4140 form softer microstructure which corresponds to lower hardness and strength. However, these steels normally used in quenched and tempered condition. The final mechanical properties depend upon their tempering temperature. Average room temperature mechanical properties in quenched and tempered condition are given in table below:

The date presented in above table is based on various tempering temperatures.

The mechanical properties of AISI 4130 and 4140 are really important as far as cold working is concerned. The ductility parameters i.e., higher percentage elongation and high reduction in area favors cold working processes like cold rolling, cold spinning and flow forming etc. Low ductility and high strength badly effect cold working processes. On the other hand, high strength requirement is prime interest in the final products. Final products are normally used in quenched and tempered condition.

4130 steel hardness chart

4140 steel hardness chart

Hardness of 4140 steel is given in table;

Tensile strength

Tensile strength is also known as ultimate tensile strength which is the maximum load bear by the specimen. AISI 4140 has higher tensile strength than AISI 4130.

Yield strength

Max. stress stand by specimen or object before plastic deformation is known as yield strength. Steel 4140 has better yield strength than 4130 material. 4130 steel yield strength is 600-1200 MPa.

Thermal conductivity

Thermal conductivity of both steels is 36-42 W/m·K.

Elongation

4041 steels have elongation in the range of 12-20 % whereas 4130 steel has 12-24 %.

Higher hardenability

High carbon content in AISI 4140 is responsible for higher hardenability than AISI 4130. However, AISI 4130 has low to medium hardenability and usually hardened in water. However, its hardenability is much higher as compared to plain carbon steels. Due to the high hardenability of AISI 4140, thicker parts can be manufactured having uniform hardness from surface to center. Relatively, inferior hardenability of AISI 4130 as compared to AISI 4140 restrict it for the manufacturing of smaller parts. For thicker parts, AISI 4130 is not a good choice for designers.

4130 vs 4140 Steel: Weldability

The weldability of any steel is inversely propositional to their carbon content. The weldability of AISI 4130 is better than AISI 4140 because of the difference in carbon percentage. Welding of AISI 4140 is crucial due to its higher carbon content. Weld cracking is a major problem in the welding of 4140 steel. Heat treatment condition also contribute in weldability of these steels. Quenched and tempered condition increase the possibility of weld cracking. However, pre and post heating, proper design, suitable heat treatment condition and selection of appropriate welding electrode are important for better weldability. Usually welding operation in the manufacturing of AISI 4140 is seldom used due to its lower weldability.

4130 vs 4140 Steel: ​Machinability

Machinability is an important consideration in the manufacturing of steel components. Usually, lower hardness of steel favors machinability and higher hardness cause wear and tear of cutting tools. In this perspective AISI 4130 has better machinability than AISI 4140 in hardened and tempered condition. Normally, machining of these steels is carried out in normalized condition. Final dimensions of the product are achieved using grinding operation.

Heat Treatment properties of steel

Heat treatment alters the microstructure of the steel which changes the mechanical properties of AISI 4130 and AISI4140 steel. Annealing, normalizing, hardening, tempering and spheroidizing are most common heat treatment processes which are applied on these steels based on their required properties. These heat treatment processes are application specified. Normally quenching and tempering is the final heat treatment process applied on these alloy steels. However, annealing and spheroidizing are usually used as intermediate process in cold forming.

Normalizing is carried out on hot worked products of AISI 4130 and AISI 4140. It creates uniform microstructure and removes internal stresses. Normalizing or spheroidizing heat treatment is commonly used to achieve softer structure in these steels which further facilitates cold working operations without cracking.

AISI 4130 steel can be tempered the broad range of 200-700 ˚C. Contrary to that, AISI 4140 has an embrittlement range between 230-375 ˚C. By tempering in this range notch toughness of AISI 4140 reduced remarkably.

Figure-1 showing impact toughness of AISI4140 steel as a function of tempering temperature.

Case Hardening

In some applications case hardening is the essential design requirement e.g., excels of tractors, crankshafts and gears of cars and motor bikes etc. Case hardening of AISI 4130 and AISI 4140 is possible using carious techniques. As far as AISI 4130 is concerned, carburizing is used to harden the surface of any component. Using carburizing surface hardening technique up to 60 HRC hardness can be achieved keeping the softer core having high toughness.

Nitriding and induction hardening are popular case hardening techniques applied on AISI 4140. After quenching and tempering, induction hardening of AISI 4140 is carried out to achieve harder case. Case hardness up to 64 HRC is possible using induction hardening of AISI 4140. The case depth of induction hardening depends upon process parameters and machine frequency. Nitriding case hardening is applied on Hydraulic barrel, Oil-pump gear, Sleeve for pneumatic tool clutch and Marine helical transmission gear etc.

Difference Between 4130 and 4140 Chart

Which is more expensive

AISI 4140 steel has higher strength and hardness as compared to AISI 4130 steel. The manufacturing processes of AISI 4140 involve expensive dies, tooling and energy. The manufacturing processes e.g., rolling, forging, cold rolling, flow forming and machining of AISI 4140 steel is expensive than AISI 4130. So, based on their manufacturing cost, you can say that, AISI 4140 is more expensive than AISI 4130.

What is 4140 Steel Used for

AISI 4140 steel finds its widespread application in automotive, agriculture, oil and gas, aerospace and marine industry. It is also used in tools and dies due to its ability to withstand high stresses and wear.

In automotive industry AISI 4140 steel is used to manufacture crank shafts, excels, camshafts and multiple type of gears. It is also used in the manufacturing of tractor excels which are used in agriculture industry. Various type of fasteners and fittings and made up of AISI 4140 steel.

Is 4140 steel good for knives?

AISI 4140 is not the best choice for manufacturing of knives. However, due to its ability to get hardened make it a choice for this application. But the final properties of the knives must be achieved by proper selection of tempering temperature to impart appropriate toughness in knives. The final product should have high hardness superior strength, and enough toughness.

What is 4130 Steel Used for

Moderately high strength, good toughness, superior weldability and excellent machining properties make AISI 4130 steel a suitable candidate in multiple applications in various industries.

In automotive industry various components e.g., landing gear parts, engine mounts, fittings and fasteners are used of AISI 4130 steel. The steel is also in structural industry in various type of beams. Multiple type of welded assemblies, fittings and rivets of AISI 4130 are also used in oil and gas, marine and automotive industries.

Pros and Cons of 4130 and 4140

AISI 4130 and AISI 4140 are member of same steel family. Slight change in their chemical composition give than a special set of properties which make them suitable for particular application. Advantages of AISI 4130 steel are good machinability, better weldability and moderately high strength. The components and assemblies, made up of AISI 4130 also exhibit good toughness and fatigue strength. Due to relatively low hardenability of AISI 4130 as compared to AISI 4130, it is usually restricted low small part size. AISI 4130 steel’s ability to get harden from surface to core is inferior as compared to AISI 4140. However, the applications where very high strength and hardness are required, AISI 4130 steel is not a good choice.

AISI 4140 has unique set of properties which make them suitable for specific applications. The applications where high strength, wear resistance and high hardness is prime design requirement, AISI 4140 will always be preferred over AISI4130. There are also few disadvantages of AISI 4140 steel, as it doesn’t have good weldability. The assemblies where welding is involved, normally AISI 4140 will not be the best choice for manufacturers. It also has inferior machinability than AISI 4130. Due to excellent hardenability id AISI 4140 steel larger parts can be manufactured using this steel.

Which is Better 4130 and 4140

Material are application specified. The answer or better or inferior depends upon the application in these steels are to be used. As AISI 4140 has very high strength, hardness and wear resistance, therefore, applications where such properties are essential it is the best choice for manufacturers. On the other hand, where high strength, excessive wear resistance and high hardness is required AISI 4130 cannot be preferred. The applications where cyclic loading is involved, welding and good machinability is essential, AISI 4130 is the best choice for as compared to AISI 4140. AISI 4130 also provide better toughness and damping in the structures. Both steels have a unique set of properties which make them suitable for specific set of applications.

How Should to Choose?

Selection of material will entirely depend upon the application. Suppose end product moderate to high strength along with good weldability and machinability, then choice will be 4130.

When to Use 4130 and 4140 Stainless Steel Fitting

Based on their unique properties AISI 4130 and AISI 4140 steel fittings are widely used in various industries based on their specific application. As you know that AISI 4140 steel is stronger and harder than AISI 4130 steel, so fittings of AISI 4140 are used where a combination of high strength, moderate toughness and resistance to wear and tear are required. These fittings are mostly used in heavy industrial machinery where dynamic or cyclic loading is absent.

As AISI 4130 is much stronger than AISI 4140, so its fittings are used in the applications where strength conditions are not severe. These fittings are used in application where high strength, good toughness and resistance to dynamic loading and vibration is required. Welding of such fittings is possible and easy as compared to AUI 4140 steel fittings.

Why Choose Tuofa to Custom Stainless Steel Parts

Tuofa is a well-known company for the production of different products composed of steel, brass, titanium and highly equipped with CNC machining and multiple other technologies. We offer you best products and our expert consultations. We are here to facilitate you with good customer services and our experts’ opinions regarding your industrial problems and help you in choosing best suitable material for your applications by saving your money and time.

FAQs about Stainless Steel Parts

Is 4140 a tool steel

AISI 4140 is not specifically used as tool steel. It belongs to medium carbon low alloy steels. Popular tool steels are H-13, D2 and K105. These steels have high carbon content and other alloying elements and usually lie in high alloy steel category.

What is stronger than 4140 steel?

AISI 4140 is stronger than AISI 4130 steel. However, there are several other steels are available which are much stronger than AISI 4140. Tools steels and maraging-300, 350 and 400 are few examples of stronger steels.

What is the difference between 4140 and 4340 steel

Percentage of carbon is the prime difference in AUSI 4130 and AISI 4140 steel. The higher percentage of carbon in AISI 4140 make it stronger and harder as compared to AISI 4130.